1. Field of the Invention
This invention relates to a tool for use in separating a two-piece plug such as an electric coupling plug for vehicular trailers.
2. Description of the Prior Art
With the use of trailers that are releasably attached to truck cabs it is necessary to run electrical current from the battery or other source to, i.e. brake lights, etc. on trailers. Because the trailers are releasable from the truck cabs for loading and unloading the wiring to the trailers is usually through a two-piece electrical plug.
There are a variety of conventional plugs, but generally all of them include a portion mounted on the front end of a trailer usually having a receptacle to receive pins from the other portion or plug of the electrical coupling. The plug is usually secured to a cable with a number of lines each running to a separate pin and the pin is mateable with the appropriate socket in the receptacle on the trailer.
Usually the receptacle portion of the coupling mounted on the trailer includes a hinged cover to protect the internal part of the receptacle from dirt and other foreign matter which may prevent proper contacts.
Heretofore when an electrical coupling is joined, that is the plug and receptacle are joined, in order to separate them the driver will pull the plug from the receptacle by hand. Generally, the conventional larger electrical couplings include opposed finger engaging projections that may be gripped and pulled on for the separation. However, with trucks subject to climatic conditions such as snow and rain quite often the couplings become jammed by dirt and snow or rain and the hand and arm are not strong enough to dislodge the plug portion from the receptacle.
Accordingly, sometimes hammers are used to hit the plug which often breaks the plug or causes damage to it. On the other hand some removals are forced by hand and arm pulling on the cable running to the plug. Such removal may not only pull the cable from the plug causing damage but the plug may give way quickly and the elbow might hit the cab, etc. This may cause elbow damage, bone breakage, or sprains.
Applicant is also aware of three types of electrical plug pullers such as those exemplified in U.S. Pat. Nos. 2,134,345; 2,894,763 and 4,614,015. In each of these patents the camming means to pry apart the plug is a permanent part of the plug. Further, they have the additional disadvantages of requiring a greater space to operate because in each of them the pressure exerted to dislodge or disconnect the plug is opposite to the direction of dislodgment. In addition, U.S. Pat. No. 2,894,763 uses the lever to dislodge from the cable a dust cover. Also the lever of U.S. Pat. No. 2,894,763 appears to push out the plug when activated.
There are also two additional prior art patents of which applicant is aware, however, in each case the present structure is not anticipated or rendered obvious. U.S. Pat. No. 2,429,327 is directed to a journal bearing extractor that includes a portion to reach inside a journal box and the tool is biased against the box in a direction opposite the withdrawal direction. The other U.S. Pat. No. 2,653,006 uses the camming principal to rotate a tool that engages a pipe to lift the same. Again, however, the fulcrum principle moves the tool in the opposite direction than the pipe to be lifted.